This invention relates generally to automated railroad operation, and more particularly, to a method and apparatus for analyzing train bearing data to reduce false stops.
Modern railroad car wheel bearings are permanently lubricated sealed units designed to last for the life of the car. However, during operation, excess friction between the axle and the bearing may produce excess heat, resulting in a condition referred to as a hot box. Moreover, when a bearing begins to operate above a predetermined temperature, continued movement of the car may cause the bearing to seize. As a result, the railroad service industry has devoted significant resources to building detectors that automatically check passing trains for hot boxes and/or hot wheels. Such detectors are generally spaced along railroad tracks at about twenty to fifty mile intervals along main-line track, and many are necessarily located in remote places.
At least one known detector includes a sensing unit lens for focusing infrared radiation that is transmitted from passing railcar bearings onto an infrared sensor. The infrared sensor is coupled to electrical circuitry which develops a signal that is representative of the journal or wheel temperature. One sensing unit is placed along one rail of the tracks and a second sensing unit is placed along the other rail of a set of tracks, so that both sides of a train can be monitored. Electrical lines connect these trackside sensing units to processing circuitry which is generally located in a “bungalow” close to the tracks. The primary use of the detector is to detect overheated bearings and alert the train operator to prevent possible damage to the railcar bearings.
In operation, if the hot box detector detects a hot box condition, a signal that indicates that the temperature of a wheel journal exceeds a predetermined value is then transmitted. Specifically, when a hot box condition is detected, i.e. the signal triggers an alarm, the train car is stopped to manually inspect the suspect wheel bearing or hot box. However, under some operating conditions, microphonic noise, sunshots, and/or sensor misalignment, for example, may cause the sensing unit to transmit a signal indicative of a hot box condition when in fact a hot box condition has not occurred. In this case, as in the previous case, the train car is stopped to manually inspect the suspect wheel bearing or hot box. However since the bearing is determined to be operating under normal conditions, this event is classified as a Hot Box System Nothing Found (NF) Stop. After a NF stop is reported, railroad personnel manually evaluate the data captured in the hot box to identify the reason for the NF stop.
While this post event analysis is useful in identifying equipment maintenance or repair concerns, the NF stop still increases the man-hours and costs of delivering products in a timely manner to their final destination. As a result, an actual or anomalous signal that is transmitted by the sensing unit indicating that a hot box condition has occurred causes the train operator to stop the train and perform a bearing inspection.